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Title: The interaction of heavy metals and mineralogy in the behaviour of clays
Author: Muththalib, Abdulla
ISNI:       0000 0004 9359 5794
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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Soil behaviour is complex in the natural environment. The contamination of soils e.g. with heavy metals can change their behaviour significantly. With the aim to understand how different clays containing varying amounts of different clay minerals behave when they come in contact with heavy metal cations, a critical review of literature and an extensive programme of laboratory testing have been conducted for this research work. The current research was carried out to investigate the effects of three of the commonly found heavy metal contaminants in soils (Cu2+, Pb2+ and Zn2+) on the behaviour of clays with different mineralogy; two pure clays (kaolin and sodium bentonite) and two reconstituted natural clays (Lucera clay and the submarine sediment from the port of Taranto), both of which are smectite- illite rich clays from South Italy. The effect of NaCl was also investigated. For each contaminant, the index properties of the clays were determined and compared. The behaviour in compression and shearing was studied from oedometer tests and triaxial tests. Scanning electron microscopy (SEM) was used to determine if the microstructure of one-dimensionally consolidated samples was also affected by the presence of heavy metal ions. Changes in mineralogy due to the presence of the heavy metals and salt were investigated by means of X-ray diffraction (XRD). The pH and electrical conductivity (EC) were also monitored. The results show that all the clays were affected by the presence of heavy metals. In kaolin, an increase in plasticity, higher compression index, lower coefficient of consolidation and lower permeability were found, while opposite effects were observed in bentonite, Lucera clay and submarine sediments. Small effects were also found on the strength. The type, concentration and combination of heavy metals were found to be all important. The effect of NaCl was more pronounced in the bentonite samples.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available